In recent years, semiconductor devices, such as flash memories, are showing a tendency to become highly integrated. Thus, a pattern size is being markedly being downscaled. When patterns are formed, a predetermined processing process, such as an oxidation process, a nitridation process, etc., may be performed on a substrate as one process of a manufacturing process.
As a method of forming the patterns, a groove is formed between circuits, and a liner film or a line is formed within the groove. With recent miniaturization, the groove is formed to obtain a high aspect ratio.
To form the liner film, it is necessary to form a film having good step coverage, which has no variation in film thickness even in an upper side surface, a middle side surface, a lower side surface and a lower portion of the groove. Due to the film having the good step coverage, a semiconductor device may have uniform characteristics between grooves, and a variation in the characteristics of the semiconductor device may be inhibited.
A process of processing the groove having a high aspect ratio by heating a gas or using a plasma-state gas has been attempted. However, it is difficult to form a film having good step coverage.
As methods of forming the film, there are a chemical vapor deposition (CVD) method and an atomic layer deposition (ALD) method in which films are formed by causing a reaction of at least two types of process gases with one another.
Since it is necessary to make uniform the characteristics of the semiconductor device, gases need to be uniformly supplied to an in-plane surface of a substrate during formation of a thin film. Thus, a single-wafer-type apparatus capable of uniformly supplying gases to a processed surface of a substrate has been developed. In the single-wafer-type apparatus, for example, a shower head including a buffer chamber is installed on the substrate to supply gases more uniformly.
To form a film using a single-wafer-type apparatus, at least two types of gases are used. The film is formed by allowing at least two types of gases to react with one another above a substrate or on the surface of the substrate. However, since the gases are supplied via the buffer chamber, byproducts may be generated in the buffer chamber due to a reaction between the gases in the buffer chamber. The generated byproducts may adversely affect characteristics of the substrate.